Efficient nonlinear reanalysis of skeletal structures using combined approximations

Non-linear reanalysis of large-scale structures usually involves much computational effort, because the set of non-linear equations must be solved repeatedly during the solution process. Various approximations that are often used for linear reanalysis are not sufficiently accurate for non-linear problems. In this study, solution procedures based on the combined approximations approach are developed and compared in terms of efficiency and accuracy. Various path-independent non-linear analysis and reanalysis problems are considered, including material non-linearity, geometric non-linearity and buckling analysis. Numerical examples demonstrate the effectiveness of the procedures presented. It is shown that in various cases accurate results can be achieved efficiently.